Pressure ulcer prevention

Risk factors

By: Mölnlycke Health Care, December 8 2011Posted in: Pressure ulcer prevention

Both intrinsic and extrinsic factors must be considered, general health, nutritional status, skin moisture, age and history of previous pressure ulcers are some of the key components that affect the risk for a patient developing pressure ulcers. Consider these with extrinsic factors like pressure and shear.
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Learn more about the aietiology of pressure ulcers

  • Intrinsic and extrinsic factors must be considered.
  • Structured risk assessment should be undertaken – Reassessment must not be forgotten.
  • Accurate documentation of each assessment is critical.
  • Prevention plan should be implemented based on risk assessment.
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Intrinsic risk factors include an assessment of the following

General health status – Does the patient present with multiple health issues? Conditions such as diabetes mellitus or respiratory conditions which are reported to predispose a patient to an increased risk.
Mobility status – Reduced mobility affects the ability to relieve pressure on vulnerable tissues.
Nutritional status – Poor nutrition can have multiple effects. Nutritional status can be assessed though simple weight monitoring and the assessment of specific indicators such as haemoglobin or serum albumin.
Skin moisture – This is a multi facetted section. Awareness of incontinence is critical however one should also consider increased body temperature and its effects.
Age – Effects of age have been shown to be associated with increased risk, however be aware that pressure ulcers can occur at any age if a mix of risk factors are present.
History of previous pressure ulcers – Healed ulcer sites represent a high risk site as scar tissue will be up to 80% original tensile strength.
Drug history – Such as use of steroids which can affect skin integrity.
Perfusion/oxygenation related issues – CVS instability, inotrope support, oxygen requirement, are reported to increase the risk of pressure ulcers.
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Extrinsic risk factors

Four extrinsic factors1, 3 are most commonly reported to pose a risk of tissue damage:

  1. Pressure1, 3
  2. Shear1, 3, 4, 5
  3. Skin microclimate1, 6 – Heat and humidity
  4. Friction1 – This force has historically been included in this list but is now discussed separately and the wounds described as friction wounds.

It is often the combination of forces that create the highest risk for a vulnerable patient. Tissue deformation happens in soft tissue, adipose tissue, connective tissue and muscle when these forces occur causing stresses and strain affecting the perfusion and cellular mechanisms essential for normal functioning. In the clinical setting non uniform forces are usually witnessed and shear forces are often present. Age, lifestyle, chronic illnesses can affect the ability to respond to these forces.

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Pressure

Definition: A load applied at right angles
to the tissue interface.

Fast facts:

  • Affected by stiffness of surface, load, tissue composition, geometry
  • Usually expressed in lb/in2 (psi) or mmHg
  • Bony prominences can be exposed to higher stresses/strains and therefore may be reflected in deep tissue injury
  • Combination of pressure with other forces may exacerbate issues
  • Pressure wounds tend to be uniform or circular in shape and tend to present with a neat appearance
  • Influence of time – High loads experienced for short periods of time can be as damaging as smaller loads experienced for long periods of time
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Shear

Definition: "An action or stress resulting from applied forces which causes or tends to cause two contiguous internal parts of the body to deform in the transverse plane."


Fast facts:

  • Increases when lateral movement occurs and also occurs when laying flat
  • When pressure load is constant and the shear forces increase the amount of tissue deformation may increase
  • Increased shear forces can exacerbate tissue damage
  • Shear inflicted ulcers often present with a less deep area swooping down to a deeper area with bruising a typical feature- skin edges may be ragged
  • Shear forces tend to cause deeper tissue damage which may not be immediately visible
  • Changes in position are likely to cause shear – For example when the head of bed is raised or lowered
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Microclimate

Definition: The local tissue temperature and moisture
at the body/support surface interface.

Fast facts:

  • Moisture is known to impact on ability of the skin to function
  • Reduce stiffness – Softens skin, maceration
  • Reduce strength – Up 96%, lead to erosion
  • Increase co-efficient of friction
  • Increase adhesion to contact surface – Increase risk of shear
  • Promote abrasion, slough and ulceration
  • Dilute skin acidity – pH shift to alkalinity
  • Elevated temperature increases metabolic rate
  • Elevated temperature leads to increased sweating
  • At interface point with support surface, body heat becomes trapped causing the skin to rapidly warm – Heat accumulates and moisture builds up
  • Animal studies have demonstrated a link between heat build up and ulcer formation2
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Friction

Definition: "The contact force parallel to the skin surface in case of sliding, i.e. sliding of the surfaces along each other."

Fast facts:

  • Friction results in the disturbance of the skin – The ability of the skin to act as a barrier may be impaired posing a higher risk of infection or the underlying structures may be exposed
  • Friction often presents as a shallow, denuded and painful area
  • The most common areas for this type of wound are the buttocks, sacrum, back, elbows and heels
  • Friction wounds may be characterized by being very untidy wounds with ragged edges
  • Friction has historically been included in the list of 4 key extrinsic factors but is now discussed separately and the wounds described as friction wounds

References

  1. National Pressure Ulcer Advisory Panel and European Pressure Ulcer Advisory Panel. Prevention and treatment of pressure ulcers: clinical practice guideline. Washington DC: National Pressure Ulcer Advisory Panel; 2009.
  2. Reaching for the moon: achieving zero pressure ulcer prevalence. J Wound Care 18(4): 137–44 Bales I, Padwojski A; 2009.
  3. Dressings can prevent pressure ulcers :fact or fallacy? The problem of pressure ulcer prevention. Wounds UK;5(4) pg 61-64; Butcher M et al; 2009.
  4. Journal of Wound, Ostomy and Continence Nursing: May/June 2007 - Volume 34 - Issue 3S - p S67 doi: 10.1097/01.WON.0000271036.00057.f8 Scientific and Clinical Abstracts From the 39th Annual Wound, Ostomy and Continence Nurses Annual Conference, Salt Lake City, Utah, June 9-13, 2007:Research Abstracts: Wound-Evidence-Based Interventions.
  5. Shear A contributory factor in pressure ulceration. A presentation aimed at clinicians and associated professional. www.npuap.org; accessed 14/12/09.
  6. Temperature-modulated pressure ulcers: a porcine model. Arch Phys Med Rehabil. 76(7):666-73; Kokate J.Y et al; 1995.
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